Bypassing critical system is not the answer
Dear Grumpy,
I have a neighbour who has a mid-2000s Montana V-6 minivan who has found a substantial amount of oil in the coolant. He has disconnected the transmission cooling lines from the radiator and installed a selfcontained cooler in front of the regular radiator for the transmission.
Out of curiosity what’s going on?
— Lost in Montana
Response,
Your neighbour is bypassing a critical system. Any modern vehicle with an automatic transmission will run the fluid through a heat exchanger built into the radiator.
When the transmission fluid is cold, heat from the engine’s coolant will help to warm up the fluid, which helps to ensure the fluid will flow when it is cold. As the transmission fluid gets hotter than the engine coolant, some heat will be transferred into the coolant, where it can be dissipated through the radiator.
I think the question here is whether the coolant ends up looking like a strawberry milkshake (transmission fluid into the coolant) or if it ends up looking like a chocolate milkshake (engine oil into the coolant)
It is unlikely there is transmission fluid in the coolant. I suppose if the transmission cooler circuit fluid pressure was excessively high for some reason, the transmission oil could get into the cooling system via a leaking heat exchanger.
More likely this is engine oil, and the oil in the coolant is an indicator of something really expensive to fix, like a head gasket, or a cracked cylinder head.
A properly functioning cooling system will operate at about 15 psi. For oil to get into the coolant, its pressure needs to be higher than 15 psi, as is the case with engine oil pressure.
Dear Todd,
I have an electrical problem with my 2003 Dodge Ram Diesel that my mechanic can’t seem to solve — it’s intermittent and usually happens when I brake. The alarm bell comes on and all warning lights come on and all the gauges go to zero for about 3 seconds. I put the car in neutral at a stop and everything is restored.
— Bells a-ringin’
Response,
Firstly, I would suggest a scan with a dealer’s DRB III scan tool. This tool will allow the tech to look at powertrain codes, body control module codes, and potential on-board network issues.
No offence to anyone in the aftermarket, but without a DRB III, your mechanic will being taking some pretty big guesses.
There was a Chrysler bulletin that referred to Erroneous Warning Light Illumination — 08-004- 03 — although it may not fix your problem.
If the truck rolled into my service bay, I would start by looking for trouble codes that would aim me in a specific direction and then I would update the instrument cluster software. Hi Todd, My problem is with a 1997 Dodge caravan SE. When I shut off the ignition and turn off the lights my headlights stay on. After a couple of hours the battery is drained. Because most of my driving is around town I have removed the high beam fuses and I have to remember to flip the high /low beam lever to high beam so that the lights don’t stay on.
— Click and No Go Response, The headlights run on what is called a multiplexed system, where the headlight switch sends a voltage signal to a body control module (BCM). A certain voltage seen by the BCM on a specific wire indicates that the driver desires “Headlights” or “High Beam.” The BCM ultimately con- trols the headlights.
The trick in diagnosing this system is to look at what the BCM is “seeing.”
For example, if the BCM is seeing a signal that would indicate that the headlights should be on, then the BCM will turn the headlights on.
There could be a problem with the headlight switch, the wiring to the BCM from the headlight switch, the wiring in the headlight circuit, or the BCM itself could be faulty.
A BCM failure is not uncommon in these vans. A new part is not available, which means a used or remanufactured part will be required. This is not a simple matter of going to a recycler and getting a new-to-you BCM.
The unit must be reprogrammed for your specific vehicle. Trust me on this one — programming is required!